1. Field of the Invention
The invention is related to the field of communication networks and, in particular, to providing notifications of waiting voicemail messages. More particularly, when a communication device is receiving phone service from a communication network that uses a different signaling protocol than the communication network in which a voicemail server is located, systems and methods are described that convert a voicemail waiting indicator from the signaling protocol of the voicemail server to the signaling protocol used by the communication network that is providing phone service to the communication device.
2. Statement of the Problem
Voicemail is a service that allows a calling party to leave a phone message for a called party when the called party is not available to answer a call. When a voicemail message is received for a called party, some voicemail services provide a notification that a voicemail message is waiting for the called party. For instance, a mobile communication network may transmit a voicemail waiting indicator to a mobile device responsive to which the mobile device may display an icon or some other indication that the called party has received a voicemail message. The called party may then retrieve the voicemail message from the communication network.
As an example of a communication network providing notification of a waiting voicemail message, assume that a called party is a mobile user receiving phone service from a 2G mobile communication network, such as a CDMA or GSM network. The mobile communication network includes a serving-Mobile Switching Center (MSC) that is serving the called party, and includes a Home Location Register (HLR) that stores a subscriber profile for the called party. The mobile communication network also includes a voicemail server that provides the voicemail service. Assume that a call to the called party is received in the mobile communication network and that the called party is not available to answer the call. When the called party is identified as being unavailable to answer the call, the serving-MSC applies a secondary treatment for the call which is routing the call to the voicemail server. The voicemail server receives the call and records a voicemail message from the calling party.
Voicemail server also transmits a voicemail waiting indicator to the serving-MSC indicating that a voicemail message is waiting in the voicemail server. The protocol used to transmit the voicemail waiting indicator depends on the signaling protocol used in the mobile communication network. For instance, if the mobile communication network comprises a CDMA network, then the voicemail waiting indicator is in ANSI protocol. If the mobile communication network comprises a GSM network, then the voicemail waiting indicator is in MAP protocol. Responsive to receiving the voicemail waiting indicator from the voicemail server, the serving-MSC transmits the appropriate voicemail waiting indicator to the mobile device of the called party. The mobile device then processes the voicemail waiting indicator to display an icon or some other indication that the called party has a voicemail message waiting in the voicemail server. The called party may then dial a directory number for the voicemail server through the mobile device to retrieve the waiting voicemail message.
Some mobile service providers allow for dual mode service. Dual mode service allows a mobile device to communicate with different types of mobile communication networks that utilize different wireless protocols. As an example, dual mode service may allow a mobile device to communicate with different types of cellular networks, such as a CDMA network and a GSM network. In another example, dual mode service may allow a mobile device to communicate with a cellular network and a wireless data network, such as a CDMA network and an IMS network. Mobile devices that are able to receive a dual mode service are referred to as dual mode devices.
One problem with notifying a called party that a voicemail message is waiting occurs when the called party is roaming in or is receiving service from a communication network that uses a different signaling protocol than the communication network in which the voicemail server is located. For instance, assume that a called party subscribes to phone service in a CDMA network. The signaling protocol used in a CDMA network is ANSI. By subscribing to phone service in the CDMA network, the called party also subscribes to a voicemail service in the CDMA network. This means that the voicemail server maintaining the voicemail account for the called party uses ANSI signaling protocol. If the called party has a dual mode device, then the called party is able to roam into service areas of other types of mobile communication networks, such as a GSM network, to receive phone service. The GSM network uses a different signaling protocol (MAP) than the CDMA network. Presently, if the voicemail server in the CDMA network records a voicemail message for the called party, then the voicemail server transmits a voicemail waiting indicator to the home MSC in the CDMA network. However, because the home MSC in the CDMA network is not presently serving the dual mode device of the called party, the home MSC is not able to transmit the voicemail waiting indicator to the dual mode device. Further, because the home MSC in the CDMA network and the serving-MSC in the GSM network use different signaling protocols for communication, the home MSC in the CDMA network is not able to transmit the voicemail waiting indicator to the serving-MSC in the GSM network. As a result, the called party is not able to receive a notification that a voicemail message is waiting in the voicemail server. The called party will not receive the voicemail waiting indicator until he/she returns to a service area of the CDMA network.